Five different strains of Salmonella (1, 2, 3, 4, 5) which can utilize lactose (Lac+) as the sole carbon source but cannot synthesize arginine (Arg-) are mixed with five other strains (6, 7, 8, 9, 10) that cannot utilize lactose (Lac-) and can make arginine (Arg+). These strains are mixed in all possible combinations and plated on appropriate plates to get Lac+ Arg+ recombinants. The following results were obtained, where H represents 'high numbers of recombinants', L refers to 'low numbers of recombinants' and O represents 'no recombinants'.
| Strain No. | 1 | 2 | 3 | 4 | 5 |
| 6 | H | O | O | H | L |
| 7 | H | O | O | H | L |
| 8 | O | H | H | O | O |
| 9 | O | L | L | O | O |
| 10 | O | H | H | O | O |
On the basis of these results, the sex type (either Hfr, F+ or F-) to each of these strains was assigned.
A. Strains 2, 3, 6, 7 are F-
B. Strains 2, 3, 5, 6, 7, 9 are F-
C. Strains 1, 4, 8, 10 are F+
D. Strains 1, 4, 8, 10 are Hfr
Which one of the following options represents a combination of all correct statements?